Fix good fish dish (6)
I believe the answer is:
scampi
'fish dish' is the definition.
(I've seen this in another clue)
'fix good' is the wordplay.
'fix' becomes 'scam' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'good' becomes 'pi' (old-fashioned term for pious).
'scam'+'pi'='SCAMPI'
Can you help me to learn more?
(Other definitions for scampi that I've seen before include "Dish of fried shrimps or prawns" , "Dish of deep-friend prawns" , "Large sauteed prawns" , "Crumby seafood dish" , "Shellfish" .)